Many modern computers rely on magnetic disk drives with which to store data, with the most popular magnetic disk drive being a hard disk drive (HDD). The HDD includes a rotating magnetic disk, write and read heads that are suspended by a suspension arm adjacent to a surface of the rotating magnetic disk, and an actuator that swings the suspension arm to place the read and write heads over selected circular tracks on the rotating disk. The read and write heads are directly located on a slider that has an air bearing surface (ABS). The suspension arm biases the slider into contact with the surface of the disk when the disk is not rotating, but when the disk rotates, air is swirled by the rotating disk. When the slider rides on the ABS, the write and read heads are employed for writing magnetic impressions to and reading magnetic impressions from the rotating disk. The read and write heads are connected to processing circuitry that operates according to computer readable programming code to implement the writing and reading functions.
The write head includes at least a coil, a write pole, and one or more return poles. When a current flows through the coil, a resulting magnetic field causes a magnetic flux to flow through the write pole, which results in a magnetic write field emitting from the tip of the write pole. This magnetic field is sufficiently strong that it locally magnetizes a portion of the adjacent magnetic disk, thereby recording a bit of data. The write field then travels through a magnetically soft underlayer of the magnetic medium to return to the return pole of the write head.
In current perpendicular magnetic recording medium head designs, the perpendicular magnetic field easily dissipates in the direction of the recording track width, producing frequent erroneous writes, to adjacent tracks. Current approaches to rectifying this problem include strategically placing shields in the vicinity of the magnetic pole, and alternatively or in combination with placing the main magnetic pole in a groove of the shielding material. This approach, however, experiences adverse data loss due to magnetic field leakage caused by vibrations and motion of the magnetic walls during operation. Ultimately, this data loss precludes desirable reliability contingent upon the existence of a margin within the HDD device wherein data may be recorded multiple times to the same location.
Thus, it would be beneficial to the field of magnetic data storage to provide a method and apparatus to overcome the above limitations of magnetic shielding approaches and thereby to reliably prevent magnetic field leakage to adjacent tracks during operation.